(Not applicable)
1. Field of the Invention
The invention relates to semiconductor processing devices, and more particularly to robots used to transport semiconductor substrates between processing stations and/or storage stations.
2. Description of Related Art
FIG. 1 shows a prior art semiconductor processing system in which a robot 10 is enclosed within a micro-environment enclosure 12. Various processing stations 14, which may include storage cassettes for holding a plurality of stacked substrates (not shown), are in communication with the micro-environment within the enclosure. Robot 10 is provided with a robot arm 16 which supports an end effector 18 used to hold semiconductor substrates as these are retrieved from the various stations 14. Disposed within micro-environment enclosure 12 is an alignment device 20 to which the semiconductor substrates are transported by robot arm 16 in order to determine and/or adjust the orientation of the semiconductor substrates. To that end, substrates such as wafers are provided with a notch at the edge, which notch is suitably detected by, for example, a photoelectric sensor provided in alignment device 20. During operation, robot 10, for example, retrieves a wafer from one of the stations 14, transports the wafer to alignment device 20 where its orientation is determined and/or adjusted, then deposits the wafer at a different station (or the same station) 14.
The aforementioned prior art system introduces several additional steps associated with the alignment device 20. For example, the substrate has to first be transported to the alignment device 20 and deposited therein, then after orientation determination and/or adjustment, the substrate has to be retrieved from alignment device 20 and then transported to the destination station. This represents a disruption in the flow path and introduces various steps which increase processing time and potential malfunction.
The invention overcomes deficiencies of the prior art by providing a system in which the substrate transporting robot is itself capable of determining the orientation of the substrate and changing this orientation. Specifically, in accordance with the invention, there is provided a robot for transporting a substrate having a reference indicium which comprises a robot arm on which an integrated edge gripper is mounted. The integrated edge gripper includes an orienting assembly for orienting the substrate such that the reference indicium is at a predetermined position in the integrated edge gripper, and a detecting assembly adapted to generate a signal indicative of the presence of the reference indicium at the predetermined position.
Further in accordance with the invention, an alignment device for use with a substantially circular substrate having a reference indicium is disclosed. The alignment device is provided with a detecting assembly adapted to generate a signal indicative of the presence of the reference indicium at a predetermined position in the alignment device and an orienting assembly for orienting the substrate such that the reference indicium is at the predetermined position. The orienting assembly includes a first set of one or more wheels each adapted to engage the edge of the substrate and each being mounted for rotation about a corresponding wheel axis; a second set of one or more wheels each adapted to engage the edge of the substrate in an engagement position and each being mounted for rotation about a corresponding wheel axis and for movement between the engagement position and a disengagement position; a first mechanical assembly, including a first motor, for rotating at least one wheel of the first set of wheels, wherein said rotation causes rotation of the substantially circular substrate; and a second mechanical assembly for moving the second set of wheels between the engagement and disengagement positions.